Improved fuel economy for the internal combustion engine-powered vehicle has long been a goal of automobile manufacturers. With the advent of the hybrid electric vehicle (HEV) a new goal, reducing engine on time, has been created. With the electric vehicle (EV) the goal is to minimize power consumption from the high voltage (HV) battery. Challenging achievement of these goals is the need to maintain a comfortable cabin.
Cabin comfort is maintained by both vehicle heating and cooling systems. When heating and cooling systems were first introduced, incoming fresh air was relied upon for both heating and cooling. As systems developed the recirculation mode was introduced into vehicle heating and cooling technology. Accordingly, today there are two ways air can enter the heating, ventilation and air conditioning (HVAC) system of an automotive air conditioning system. One of these ways is the fresh air mode. The other is the recirculation air mode.
However, for all types of vehicles there is a trade-off between these parameters. Particularly, for the internal combustion (IC) vehicle (including the hybrid electric vehicle [HEV]), fuel economy will suffer to maximize heating/cooling performance. In the electric vehicle, battery power consumption will be increased to maximize heating/cooling performance. Today the selection of the air mode is often made without consideration for the optimization of heating/cooling performance, fuel economy and/or high voltage (HV) battery power consumption. If the management of the air entering the HVAC is not managed carefully these parameters may not be optimized. Particularly, if the fresh air mode is selected as the source of air for the HVAC system in hot weather, this air mode will add more cooling load to the compressor. On the other hand, if the fresh air mode is selected as the source of air for the HVAC system in cold weather, this air mode will slow down heater/defrost performance. Yet when the recirculation mode is selected to provide 100% of the incoming air for the HVAC, a potential result, in certain ambient conditions, is cabin fogging.
Accordingly, as is often the case, there is room for improvement in the art of controlling the selection of incoming air to achieve parameter optimization.